Brake light sticking

Hi all, just got back from uni and eagerly pulled off the cover and took the bike for a spin, while doing some checks I realised the brake light was sticking on when the rear brake is depressed and released. It doesn't appear to be related to the return of the pedal, since pulling the pedal up manually doesn't sort it out. Does anyone have any idea of what the problem might be, and how I might go about fixing it? Before I dig out the tools and go rooting through following wires around.

Thanks

Quite often the plunger in the brake light switch will corrode or get covered in crud and as a result wont return fully. Clean and spray with WD40, this normally sorts it out.
Also check that the switch is seated in it's holder properly, and adjust if required.

Sounds as though the plunger may be stuck on the brake light switch, you can prove the point by unplugging one of the wires to it. You may be able to breath some life into it with some contact cleaner.
Touch wood I've not had any trouble with the rear switch, the front one has failed twice over the years though.

Edit: Andy got in there first!

On mine iirc there is a twisty part that you can use to adjust the plunger/cable. I'm not sure if I'm thinking of my cb500 or my cbf125 though

Thanks guys, I'm guessing this would be the right part

http://www.wemoto.com/bikes/honda/cb_500_w_x/98-99/picture/brake_light_switch_-_rear/

Will get the tools out tomorrow and take a look at it, see if I can clear it out for now, but for the sake of 6 quid I think it's probably worth just outright replacing, and then it's gonna be perfectly clean inside - probably a damn sight better than I'll be able to get

That's the one, as you say not worth messing around for the sake of £6.

Took a look earlier today when there was a break in the rain, and of course the bolt holding the switch assembly on is well and truly stuck. Tried it with two different allen keys, one old and worn the other pretty new and sharp, both ended up rounding the head a little bit with no movement. The rain came again so I packed up the tools and left it at that. Gonna go out again tomorrow and try a few things to get it out, then measure it to grab a new one while I'm at it. It seems I always end up having to deal with stuck screws, I really should be better prepared for it tbh.

Ah well, my dad said he thinks there's an impact driver in the garage (somewhere), so gonna hunt around for that, and if the worst comes to the worst, I'll try cutting a slot or drilling it out.

The two bolts hold on the brake master cylinder. There's no need to remove it. The switch just screws into a thin steel bracket by hand.

Got it all sorted now, with the new part fitted. As it turns out, the one I was sent was slightly different to the original, having a smaller hole without beveling around it, so it was a right job trying to get the spring on it. Also took me a while trying to figure out how to unscrew it by hand, before realising that there is a cutout on the bracket that means the easy way to take it out is to pull it up and slide the pin through the cutout out of the bracket.

Thanks for all the help, especially you Andy, had you not said I probably would have spent far too long trying to undo the stuck bolt holding on the master cylinder